This invention relates to power take-off (PTO) devices and has been conceived in connection with the PTO of an agricultural tractor but it is understood that the invention is applicable to any apparatus having a PTO arrangement.
The PTO of a tractor typically comprises an output shaft of the tractor gearbox, which shaft may be rearwardly directed so as to be readily coupled to an ancillary piece of equipment, such as a baler or forage harvester, for example, the coupling in some cases being by way of a shaft mounted in a cylindrical housing and connected at one end to the PTO shaft via a universal joint, and coupled at the other end to the ancillary equipment, again via a universal joint. The basic coupling is protected by some form of shielding for safety reasons. This still remains a potentially hazardous component, as does the PTO shaft itself if it is left uncovered. The PTO shaft of a tractor is typically driven at 1,000 rpm and even in a two-speed arrangement, the lower speed is still to be between 500 and 700 rpm so that in either event, if any of the rotating elements are touched or if loose clothing is caught therein, this can result in very serious, if not fatal, injuries. Also, an untimely and unexpected engagement of the drive to the ancillary equipment is potentially very hazardous.